Put the extra virgin olive oil, celery, carrot and onion in a big pot and sauté them for a few minutes, until the vegetables are soft.
Add the mince, stir well and break all lumps with a wooden spoon. When the meat is nicely browned, add the wine and cook off the alcohol by increasing the flame.
Add the tomato purée, salt and pepper and fill with water till the brim of the pot. Lower the flame to medium-low, cover and let the sauce cook for at least 1 hour, or until thick. Keep aside.
Put the butter in a non stick pot and let it melt.
Add the flour and whisk constantly until well incorporated. Let it cook for a minute or two.
Now start adding hot milk little by little, while mixing continuously. Do not add the next batch until the milk is well incorporated.
Keep doing so until all the milk is incorporated. Add salt and nutmeg and cook it on a low flame for 5 minutes or until it thickens.
When ready, cover it to prevent a film forming on the surface.
Cook the Penne in salted boiling water. If you are using an Italian brand, the exact cooking time is usually written on the packet. In this case, cook it only for HALF the time and then drain it (the pasta will keep cooking in the oven).
Put the drained pasta in the pot with the meat sauce, add the Béchamel Sauce too and mix well. Add the chopped mozzarella, provolone and 2/3 of the grated Parmigiano Reggiano. Mix well.
Pour into an oven dish and spread uniformly. Sprinkle the top with the remaining grated Parmigiano Reggiano and cover it with aluminium foil.
Bake in a pre-heated oven at 180°C – 355°F for 15 minutes, then uncover it and grill it for 5 minutes.